. The ratio between the black hole Schwarzschild radius and the observer distance to it is 1:9. Of note is the gravitational lensing effect known as an Einstein ring, which produces a set of two fairly bright and large but highly distorted images of the Cloud as compared to its actual angular size.]] A black hole is a region of space from which nothing, not even light, can escape. It is the result of the deformation of spacetime caused by a very compact mass. Around a black hole there is an undetectable surface which marks the point of no return. This surface is called an event horizon. It is called "black" because it absorbs all the light that hits it, reflecting nothing, just like a perfect black body in thermodynamics. Quantum mechanics predicts that black holes also emit radiation like a black body with a finite temperature. This temperature decreases with the mass of the black hole, making it difficult to observe this radiation for black holes of stellar mass.

Despite its invisible interior, a black hole can be observed through its interaction with other matter. A black hole can be inferred by tracking the movement of a group of stars that orbit a region in space. Alternatively, when gas falls into a stellar black hole from a companion star, the gas spirals inward, heating to very high temperatures and emitting large amounts of radiation that can be detected from earthbound and Earth-orbiting telescopes.

Astronomers have identified numerous stellar black hole candidates, and have also found evidence of supermassive black holes at the center of galaxies. In 1998, astronomers found compelling evidence that a supermassive black hole of more than 2 million solar masses is located near the Sagittarius A* region in the center of the Milky Way galaxy. Recent results indicate that the supermassive black hole is more than 4 million solar masses.

History

ing by a black hole which distorts the image of a galaxy in the background (click here for larger animation)]] The idea of a body so massive that even light could not escape was first put forward by geologist John Michell in a letter written to Henry Cavendish in 1783 to the Royal Society:

}} In 1796, mathematician Pierre-Simon Laplace promoted the same idea in the first and second editions of his book Exposition du système du Monde (it was removed from later editions). Such "dark stars" were largely ignored in the nineteenth century, since it was not understood how a massless wave such as light could be influenced by gravity.

General relativity

In 1915, Albert Einstein developed his theory of general relativity, having earlier shown that gravity does influence light's motion. A few months later, Karl Schwarzschild gave the solution for the gravitational field of a point mass and a spherical mass. This solution had a peculiar behaviour at what is now called the Schwarzschild radius, where it became singular, meaning that some of the terms in the Einstein equations became infinite. The nature of this surface was not quite understood at the time. In 1924, Arthur Eddington showed that the singularity disappeared after a change of coordinates (see Eddington–Finkelstein coordinates), although it took until 1933 for Georges Lemaître to realize that this meant the singularity at the Schwarzschild radius was an unphysical coordinate singularity.

In 1931, Subrahmanyan Chandrasekhar calculated, using general relativity, that a non-rotating body of electron-degenerate matter above a certain limiting mass (now called the Chandrasekhar limit at 1.44 solar masses) must have an infinite density. In other words, the object must have a radius of zero. They were partly correct: a white dwarf slightly more massive than the Chandrasekhar limit will collapse into a neutron star, which is itself stable because of the Pauli exclusion principle. But in 1939, Robert Oppenheimer and others predicted that neutron stars above approximately three solar masses (the Tolman–Oppenheimer–Volkoff limit) would collapse into black holes for the reasons presented by Chandrasekhar, and concluded that no law of physics was likely to intervene and stop at least some stars from collapsing to black holes.

Oppenheimer and his co-authors interpreted the singularity at the boundary of the Schwarzschild radius as indicating that this was the boundary of a bubble in which time stopped. This is a valid point of view for external observers, but not for infalling observers. Because of this property, the collapsed stars were called "frozen stars," because an outside observer would see the surface of the star frozen in time at the instant where its collapse takes it inside the Schwarzschild radius.

Golden age

In 1958, David Finkelstein identified the Schwarzschild surface r = 2m [in geometrized units, i.e. 2Gm/c², where r is the radius of the surface and m is the mass of the black hole] as an event horizon, "a perfect unidirectional membrane: causal influences can cross it in only one direction". This did not strictly contradict Oppenheimer's results, but extended them to include the point of view of infalling observers. Finkelstein's solution extended the Schwarzschild solution for the future of observers falling into the black hole. A complete extension had already been found by Martin Kruskal, who was urged to publish it.

These results came at the beginning of the golden age of general relativity, which was marked by general relativity and black holes becoming mainstream subjects of research. This process was helped by the discovery of pulsars in 1967, which were within a few years shown to be rapidly rotating neutron stars. Until that time, neutron stars, like black holes, were regarded as just theoretical curiosities; but the discovery of pulsars showed their physical relevance and spurred a further interest in all types of compact objects that might be formed by gravitational collapse.

In this period more general black hole solutions were found. In 1963, Roy Kerr found the exact solution for a rotating black hole. Two years later Ezra T. Newman found the axisymmetric solution for a black hole which is both rotating and electrically charged. Through the work of Werner Israel, Brandon Carter, and D. C. Robinson the no-hair theorem emerged, stating that a stationary black hole solution is completely described by the three parameters of the Kerr–Newman metric; mass, angular momentum, and electric charge. and Stephen Hawking used global techniques to prove that singularities are generic.

Work by James Bardeen, Jacob Bekenstein, Carter, and Hawking in the early 1970s led to the formulation of the laws of black hole mechanics. These laws describe the behaviour of a black hole in close analogy to the laws of thermodynamics by relating mass to energy, area to entropy, and surface gravity to temperature. The analogy was completed when Hawking, in 1974, showed that quantum field theory predicts that black holes should radiate like a black body with a temperature proportional to the surface gravity of the black hole. After Wheeler's use of the term, it was quickly adopted in general use.

Properties and structure

The no-hair theorem states that, once it achieves a stable condition after formation, a black hole has only three independent physical properties: mass, charge, and angular momentum. Any two black holes that share the same values for these properties, or parameters, are indistinguishable according to classical (i.e. non-quantum) mechanics.

These properties are special because they are visible from outside the black hole. For example, a charged black hole repels other like charges just like any other charged object. Similarly, the total mass inside a sphere containing a black hole can be found by using the gravitational analog of Gauss's law, the ADM mass, far away from the black hole. Likewise, the angular momentum can be measured from far away using frame dragging by the gravitomagnetic field.

When an object falls into a black hole, any information about the shape of the object or distribution of charge on it is evenly distributed along the horizon of the black hole, and is lost to outside observers. The behavior of the horizon in this situation is closely analogous to that of a conductive stretchy membrane with friction and electrical resistance, a dissipative system (see membrane paradigm). This is different from other field theories like electromagnetism, which does not have any friction or resistivity at the microscopic level, because they are time-reversible. Because the black hole eventually achieves a stable state with only three parameters, there is no way to avoid losing information about the initial conditions: the gravitational and electric fields of the black hole give very little information about what went in. The information that is lost includes every quantity that cannot be measured far away from the black hole horizon, including the total baryon number, lepton number, and all the other nearly conserved pseudo-charges of particle physics. This behavior is so puzzling that it has been called the black hole information loss paradox.

Physical properties

The simplest black hole has mass but neither electric charge nor angular momentum. These black holes are often referred to as Schwarzschild black holes after the physicist Karl Schwarzschild who discovered this solution in 1915. According to Birkhoff's theorem, it is the only vacuum solution that is spherically symmetric. This means that there is no observable difference between the gravitational field of such a black hole and that of any other spherical object of the same mass. The popular notion of a black hole "sucking in everything" in its surroundings is therefore only correct near the black hole horizon; far away, the external gravitational field is identical to that of any other body of the same mass.

Solutions describing more general black holes also exist. Charged black holes are described by the Reissner–Nordström metric, while the Kerr metric describes a rotating black hole. The most general stationary black hole solution known is the Kerr–Newman metric, which describes a black hole with both charge and angular momentum.

While the mass of a black hole can take any positive value, the charge and angular momentum are constrained by the mass. In Planck units, the total electric charge Q and the total angular momentum J are expected to satisfy :$Q^2+\backslash left\; (\; \backslash tfrac\{J\}\{M\}\; \backslash right\; )^2\backslash le\; M^2\backslash ,$ for a black hole of mass M. Black holes saturating this inequality are called extremal. Solutions of Einstein's equations violating the inequality exist, but do not have a horizon. These solutions have naked singularities and are deemed unphysical. The cosmic censorship hypothesis rules out the formation of such singularities through the gravitational collapse of realistic matter. This is supported by numerical simulations.

Due to the relatively large strength of the electromagnetic force, black holes forming from the collapse of stars are expected to retain the nearly neutral charge of the star. Rotation, however, is expected to be a common feature of compact objects, and the black-hole candidate binary X-ray source GRS 1915+105 appears to have an angular momentum near the maximum allowed value.

Black holes are commonly classified according to their mass, independent of angular momentum J or electric charge Q. The size of a black hole, as determined by the radius of the event horizon, or Schwarzschild radius, is roughly proportional to the mass M through :$r\_\backslash mathrm\{sh\}\; =\backslash frac\{2GM\}\{c^2\}\; \backslash approx\; 2.95\backslash ,\; \backslash frac\{M\}\{M\_\backslash mathrm\{Sun\}\}~\backslash mathrm\{km,\}$ where r_sh is the Schwarzschild radius and M_Sun is the mass of the Sun. This relation is exact only for black holes with zero charge and angular momentum, for more general black holes it can differ up to a factor of 2. The table on the right lists the various classes of black hole that are distinguished.

Event horizon

The defining feature of a black hole is the appearance of an event horizon—a boundary in spacetime through which matter and light can only pass inward towards the mass of the black hole. Nothing, not even light, can escape from inside the event horizon. The event horizon is referred to as such because if an event occurs within the boundary, information from that event cannot reach an outside observer, making it impossible to determine if such an event occurred.

As predicted by general relativity, the presence of a large mass deforms spacetime in such a way that the paths taken by particles bend towards the mass. At the event horizon of a black hole, this deformation becomes so strong that there are no paths that lead away from the black hole.

To a distant observer, clocks near a black hole appear to tick more slowly than those further away from the black hole. Due to this effect, known as gravitational time dilation, an object falling into a black hole appears to slow down as it approaches the event horizon, taking an infinite time to reach it. At the same time, all processes on this object slow down causing emitted light to appear redder and dimmer, an effect known as gravitational redshift. Eventually, at a point just before it reaches the event horizon, the falling object becomes so dim that it can no longer be seen.

On the other hand, an observer falling into a black hole does not notice any of these effects as he crosses the event horizon. According to his own clock, he crosses the event horizon after a finite time, although he is unable to determine exactly when he crosses it, as it is impossible to determine the location of the event horizon from local observations.

For a non rotating (static) black hole, the Schwarzschild radius delimits a spherical event horizon. The Schwarzschild radius of an object is proportional to the mass. Rotating black holes have distorted, nonspherical event horizons. Since the event horizon is not a material surface but rather merely a mathematically defined demarcation boundary, nothing prevents matter or radiation from entering a black hole, only from exiting one. The description of black holes given by general relativity is known to be an approximation, and some scientists expect that quantum gravity effects will become significant near the vicinity of the event horizon. This would allow observations of matter near a black hole's event horizon to be used to indirectly study general relativity and proposed extensions to it.

Singularity

At the center of a black hole as described by general relativity lies a gravitational singularity, a region where the spacetime curvature becomes infinite. For a non-rotating black hole this region takes the shape of a single point and for a rotating black hole it is smeared out to form a ring singularity lying in the plane of rotation. In both cases the singular region has zero volume. It can also be shown that the singular region contains all the mass of the black hole solution. The singular region can thus be thought of as having infinite density.

An observer falling into a Schwarzschild black hole (i.e. non-rotating and no charges) cannot avoid the singularity. Any attempt to do so will only shorten the time taken to get there. When they reach the singularity, they are crushed to infinite density and their mass is added to the total of the black hole. Before that happens, they will have been torn apart by the growing tidal forces in a process sometimes referred to as spaghettification or the noodle effect.

In the case of a charged (Reissner–Nordström) or rotating (Kerr) black hole it is possible to avoid the singularity. Extending these solutions as far as possible reveals the hypothetical possibility of exiting the black hole into a different spacetime with the black hole acting as a wormhole. The possibility of traveling to another universe is however only theoretical, since any perturbation will destroy this possibility. It also appears to be possible to follow closed timelike curves (going back to one's own past) around the Kerr singularity, which lead to problems with causality like the grandfather paradox. It is expected that none of these peculiar effects would survive in a proper quantum mechanical treatment of rotating and charged black holes.

The appearance of singularities in general relativity is commonly perceived as signaling the breakdown of the theory. This breakdown, however, is expected; it occurs in a situation where quantum mechanical effects should describe these actions due to the extremely high density and therefore particle interactions. To date it has not been possible to combine quantum and gravitational effects into a single theory. It is generally expected that a theory of quantum gravity will feature black holes without singularities.

Photon sphere

The photon sphere is a spherical boundary of zero thickness such that photons moving along tangents to the sphere will be trapped in a circular orbit. For non-rotating black holes, the photon sphere has a radius 1.5 times the Schwarzschild radius. The orbits are dynamically unstable, hence any small perturbation (such as a particle of infalling matter) will grow over time, either setting it on an outward trajectory escaping the black hole or on an inward spiral eventually crossing the event horizon.

While light can still escape from inside the photon sphere, any light that crosses the photon sphere on an inbound trajectory will be captured by the black hole. Hence any light reaching an outside observer from inside the photon sphere must have been emitted by objects inside the photon sphere but still outside of the event horizon.

Other compact objects, such as neutron stars, can also have photon spheres. This follows from the fact that the gravitational field of an object does not depend on its actual size, hence any object that is smaller than 1.5 times the Schwarzschild radius corresponding to its mass will indeed have a photon sphere.

Ergosphere

Rotating black holes are surrounded by a region of spacetime in which it is impossible to stand still, called the ergosphere. This is the result of a process known as frame-dragging; general relativity predicts that any rotating mass will tend to slightly "drag" along the spacetime immediately surrounding it. Any object near the rotating mass will tend to start moving in the direction of rotation. For a rotating black hole this effect becomes so strong near the event horizon that an object would have to move faster than the speed of light in the opposite direction to just stand still.

The ergosphere of a black hole is bounded by the (outer) event horizon on the inside and an oblate spheroid, which coincides with the event horizon at the poles and is noticeably wider around the equator. The outer boundary is sometimes called the ergosurface.

Objects and radiation can escape normally from the ergosphere. Through the Penrose process, objects can emerge from the ergosphere with more energy than they entered. This energy is taken from the rotational energy of the black hole causing it to slow down.

Formation and evolution

Considering the exotic nature of black holes, it may be natural to question if such bizarre objects could exist in nature or to suggest that they are merely pathological solutions to Einstein's equations. Einstein himself wrongly thought that black holes would not form, because he held that the angular momentum of collapsing particles would stabilize their motion at some radius. This led the general relativity community to dismiss all results to the contrary for many years. However, a minority of relativists continued to contend that black holes were physical objects, and by the end of the 1960s, they had persuaded the majority of researchers in the field that there is no obstacle to forming an event horizon.

Once an event horizon forms, Roger Penrose proved that a singularity will form somewhere inside it. The primary formation process for black holes is expected to be the gravitational collapse of heavy objects such as stars, but there are also more exotic processes that can lead to the production of black holes.

Gravitational collapse

Gravitational collapse occurs when an object's internal pressure is insufficient to resist the object's own gravity. For stars this usually occurs either because a star has too little "fuel" left to maintain its temperature through stellar nucleosynthesis, or because a star which would have been stable receives extra matter in a way which does not raise its core temperature. In either case the star's temperature is no longer high enough to prevent it from collapsing under its own weight (the ideal gas law explains the connection between pressure, temperature, and volume).

The collapse may be stopped by the degeneracy pressure of the star's constituents, condensing the matter in an exotic denser state. The result is one of the various types of compact star. Which type of compact star is formed depends on the mass of the remnant — the matter left over after changes triggered by the collapse (such as supernova or pulsations leading to a planetary nebula) have blown away the outer layers. Note that this can be substantially less than the original star — remnants exceeding 5 solar masses are produced by stars which were over 20 solar masses before the collapse.

While most of the energy released during gravitational collapse is emitted very quickly, an outside observer does not actually see the end of this process. Even though the collapse takes a finite amount of time from the reference frame of infalling matter, a distant observer sees the infalling material slow and halt just above the event horizon, due to gravitational time dilation. Light from the collapsing material takes longer and longer to reach the observer, with the light emitted just before the event horizon forms delayed an infinite amount of time. Thus the external observer never sees the formation of the event horizon; instead, the collapsing material seems to become dimmer and increasingly red-shifted, eventually fading away.

Primordial black holes in the Big Bang

Gravitational collapse requires great densities. In the current epoch of the universe these high densities are only found in stars, but in the early universe shortly after the big bang densities were much greater, possibly allowing for the creation of black holes. The high density alone is not enough to allow the formation of black holes since a uniform mass distribution will not allow the mass to bunch up. In order for primordial black holes to form in such a dense medium, there must be initial density perturbations which can then grow under their own gravity. Different models for the early universe vary widely in their predictions of the size of these perturbations. Various models predict the creation of black holes, ranging from a Planck mass to hundreds of thousands of solar masses. Primordial black holes could thus account for the creation of any type of black hole.

High-energy collisions

Gravitational collapse is not the only process that could create black holes. In principle, black holes could also be created in high-energy collisions that create sufficient density. However, to date, no such events have ever been detected either directly or indirectly as a deficiency of the mass balance in particle accelerator experiments. This suggests that there must be a lower limit for the mass of black holes. Theoretically, this boundary is expected to lie around the Planck mass (m_P = ≈ ≈ ), where quantum effects are expected to make the theory of general relativity break down completely. This would put the creation of black holes firmly out of reach of any high energy process occurring on or near the Earth. Certain developments in quantum gravity however suggest that the Planck mass could be much lower: some braneworld scenarios for example put it much lower, maybe even as low as This would make it possible for micro black holes to be created in the high energy collisions occurring when cosmic rays hit the Earth's atmosphere, or possibly in the new Large Hadron Collider at CERN. These theories are however very speculative, and the creation of black holes in these processes is deemed unlikely by many specialists. Even if such micro black holes should be formed in these collisions, it is expected that they would evaporate in about 10⁻²⁵ seconds, posing no threat to Earth

Growth

Once a black hole has formed, it can continue to grow by absorbing additional matter. Any black hole will continually absorb gas and interstellar dust from its direct surroundings and omnipresent cosmic background radiation. This is the primary process through which supermassive black holes seem to have grown.

Another possibility is for a black hole to merge with other objects such as stars or even other black holes. This is thought to have been important especially for the early development of supermassive black holes, which are thought to have formed from the coagulation of many smaller objects.

Evaporation

In 1974, Stephen Hawking showed that black holes are not entirely black but emit small amounts of thermal radiation. He got this result by applying quantum field theory in a static black hole background. The result of his calculations is that a black hole should emit particles in a perfect black body spectrum. This effect has become known as Hawking radiation. Since Hawking's result, many others have verified the effect through various methods. If his theory of black hole radiation is correct, then black holes are expected to emit a thermal spectrum of radiation, and thereby lose mass, because according to the theory of relativity mass is just highly condensed energy (E = mc²).

On the other hand, if a black hole is very small the radiation effects are expected to become very strong. Even a black hole that is heavy compared to a human would evaporate in an instant. A black hole the weight of a car (~10⁻²⁴ m) would only take a nanosecond to evaporate, during which time it would briefly have a luminosity more than 200 times that of the sun. Lighter black holes are expected to evaporate even faster, for example a black hole of mass 1 TeV/c² would take less than 10⁻⁸⁸ seconds to evaporate completely. Of course, for such a small black hole quantum gravitation effects are expected to play an important role and could even although current developments in quantum gravity do not indicate so hypothetically make such a small black hole stable.

Observational evidence

By their very nature, black holes do not directly emit any signals other than the hypothetical Hawking radiation; since the Hawking radiation for an astrophysical black hole is predicted to be very weak, this makes it impossible to directly detect astrophysical black holes from the Earth. A possible exception to the Hawking radiation being weak is the last stage of the evaporation of light (primordial) black holes; searches for such flashes in the past has proven unsuccessful and provides stringent limits on the possibility of existence of light primordial black holes. NASA's Fermi Gamma-ray Space Telescope launched in 2008 will continue the search for these flashes.

Astrophysicists searching for black holes thus have to rely on indirect observations. A black hole's existence can sometimes be inferred by observing its gravitational interactions with its surroundings.

Accretion of matter

Due to conservation of angular momentum, gas falling into the gravitational well created by a massive object will typically form a disc-like structure around the object. Friction within the disc causes angular momentum to be transported outward allowing matter to fall further inward releasing potential energy and increasing the temperature of the gas. In the case of compact objects such as white dwarfs, neutron stars, and black holes, the gas in the inner regions becomes so hot that it will emit vast amounts of radiation (mainly X-rays), which may be detected by telescopes. This process of accretion is one of the most efficient energy producing process known; up to 40% of the rest mass of the accreted material can be emitted in radiation.

X-ray binaries

X-ray binaries are binary star systems that are luminous in the X-ray part of the spectrum. These X-ray emissions are generally thought to be caused by one of the component stars being a compact object accreting matter from the other (regular) star. The presence of an ordinary star in such a system provides a unique opportunity for studying the central object and determining if it might be a black hole.

If such a system emits signals that can be directly traced back to the compact object, it cannot be a black hole. The absence of such a signal does, however, not exclude the possibility that the compact object is a neutron star. By studying the companion star it is often possible to obtain the orbital parameters of the system and obtain an estimate for the mass of the compact object. If this is much larger than the Tolman–Oppenheimer–Volkoff limit (that is, the maximum mass a neutron star can have before collapsing) then the object cannot be a neutron star and is generally expected to be a black hole.

The first strong candidate for a black hole, Cygnus X-1, was discovered in this way by Charles Thomas Bolton and Webster and Murdin in 1972. Some doubt, however, remained due to the uncertainties resultant from the companion star being much heavier than the candidate black hole. Because, if the object at the center of the disc had a solid surface, it would emit large amounts of radiation as the highly energetic gas hits the surface, an effect that is observed for neutron stars in a similar state.

Gamma ray bursts

Intense but one-time gamma ray bursts (GRBs) may signal the birth of "new" black holes, because astrophysicists think that GRBs are caused either by the gravitational collapse of giant stars or by collisions between neutron stars, and both types of event involve sufficient mass and pressure to produce black holes. It appears that a collision between a neutron star and a black hole can also cause a GRB, so a GRB is not proof that a "new" black hole has been formed. All known GRBs come from outside our own galaxy, and most come from billions of light years away so the black holes associated with them are billions of years old.

Galactic nuclei

in this image comes from an active galactic nucleus that may contain a supermassive black hole. Credit: Hubble Space Telescope/NASA/ESA.]]

It is now widely accepted that the center of every or at least nearly every galaxy contains a supermassive black hole. The close observational correlation between the mass of this hole and the velocity dispersion of the host galaxy's bulge, known as the M-sigma relation, strongly suggests a connection between the formation of the black hole and the galaxy itself.

For decades, astronomers have used the term "active galaxy" to describe galaxies with unusual characteristics, such as unusual spectral line emission and very strong radio emission. However, theoretical and observational studies have shown that the active galactic nuclei (AGN) in these galaxies may contain supermassive black holes.

Currently, the best evidence for a supermassive black hole comes from studying the proper motion of stars near the center of our own Milky Way. Since 1995 astronomers have tracked the motion of 90 stars in a region called Sagittarius A*. By fitting their motion to Keplerian orbits they were able to infer in 1998 that 2.6 million solar masses must be contained in a volume with a radius of 0.02 lightyears. Since then one of the stars—called S2—has completed a full orbit. From the orbital data they were able to place better constraints on the mass and size of the object causing the orbital motion of stars in the Sagittarius A* region, finding that there is a spherical mass of 4.3 million solar masses contained within a radius of less than 0.002 lightyears.

Alternatives

The evidence for stellar black holes strongly relies on the existence of an upper limit for the mass of a neutron star. The size of this limit heavily depends on the assumptions made about the properties of dense matter. New exotic phases of matter could push up this bound. and some supersymmetric models predict the existence of Q stars. Some extensions of the standard model posit the existence of preons as fundamental building blocks of quarks and leptons which could hypothetically form preon stars. These hypothetical models could potentially explain a number of observations of stellar black hole candidates. However, it can be shown from general arguments in general relativity that any such object will have a maximum mass. In recent years, much attention has been drawn by the fuzzball model in string theory. Based on calculations in specific situations in string theory, the proposal suggest that generically the individual states of a black hole solution do not have an event horizon or singularity (and can thus not really be considered to be a black hole), but that for a distant observer the statistical average of such states does appear just like an ordinary black hole in general relativity.

Open questions

Entropy and thermodynamics

can create microscopic black holes, it is expected that all types of particles will be emitted by black hole evaporation, providing key evidence for any grand unified theory. Above are the high energy particles produced in a gold ion collision on the RHIC.]] In 1971, Stephen Hawking showed under general conditions that the total area of the event horizons of any collection of classical black holes can never decrease, even if they collide and merge. This result, now known as the second law of black hole mechanics, is remarkably similar to the second law of thermodynamics, which states that the total entropy of a system can never decrease. As with classical objects at absolute zero temperature, it was assumed that black holes had zero entropy. If this were the case, the second law of thermodynamics would be violated by entropy-laden matter entering the black hole, resulting in a decrease of the total entropy of the universe. Therefore, Jacob Bekenstein proposed that a black hole should have an entropy, and that it should be proportional to its horizon area.

The link with the laws of thermodynamics was further strengthened by Hawking's discovery that quantum field theory predicts that a black hole radiates blackbody radiation at a constant temperature. This seemingly causes a violation of the second law of black hole mechanics, since the radiation will carry away energy from the black hole causing it to shrink. The radiation, however also carries away entropy, and it can be proven under general assumptions that the sum of the entropy of the matter surrounding the black hole and one quarter of the area of the horizon as measured in Planck units is in fact always increasing. This allows the formulation of the first law of black hole mechanics as an analogue of the first law of thermodynamics, with the mass acting as energy, the surface gravity as temperature and the area as entropy.

Although general relativity can be used to perform a semi-classical calculation of black hole entropy, this situation is theoretically unsatisfying. In statistical mechanics, entropy is understood as counting the number of microscopic configurations of a system which have the same macroscopic qualities (such as mass, charge, pressure, etc.). Without a satisfactory theory of quantum gravity, one cannot perform such a computation for black holes. Some progress has been made in various approaches to quantum gravity. In 1995, Strominger and Vafa showed that counting the microstates of a specific supersymmetric black hole in string theory reproduced the Bekenstein–Hawking entropy. Since then, similar results have been reported for different black holes both in string theory and in other approaches to quantum gravity like loop quantum gravity.

Black hole unitarity

An open question in fundamental physics is the so-called information loss paradox, or black hole unitarity paradox. Classically, the laws of physics are the same run forward or in reverse (T-symmetry). Liouville's theorem dictates conservation of phase space volume, which can be thought of as "conservation of information", so there is some problem even in classical physics. In quantum mechanics, this corresponds to a vital property called unitarity, which has to do with the conservation of probability (it can also be thought of as a conservation of quantum phase space volume as expressed by the density matrix).

See also

Black holes in fiction

Black string

Kugelblitz (astrophysics)

List of black holes

Susskind-Hawking battle

Timeline of black hole physics

White hole

Wormhole

Notes

}}

Further reading

;Popular reading . . . . . . , poem. .

;University textbooks and monographs , the lecture notes on which the book was based are available for free from Sean Carroll's website. . . . . . . . .

;Review papers Lecture notes from 2005 SLAC Summer Institute.

External links

Stanford Encyclopedia of Philosophy: "Singularities and Black Holes" by Erik Curiel and Peter Bokulich.

"Black hole" on Scholarpedia.

Black Holes: Gravity's Relentless Pull – Interactive multimedia Web site about the physics and astronomy of black holes from the Space Telescope Science Institute

FAQ on black holes

"Schwarzschild Geometry"

Advanced Mathematics of Black Hole Evaporation

;Videos

16-year long study tracks stars orbiting Milky Way black hole

Yale University Video Lecture: Introduction to Black Holes at Google Video.

Movie of Black Hole Candidate from Max Planck Institute

Black holes Category:Dark matter Category:Relativity Category:Galaxies

Jimi Tenor (born Lahti, 1965 as Lassi Lehto) is a Finnish musician. His name is a combination of the first name of his youth idol Jimmy Osmond and the tenor saxophone. His band Jimi Tenor & His Shamans published its first album in 1988, Jimi's first solo album appeared in 1994. "Take Me Baby" became his first hit in 1994. He has released albums on Sähkö Recordings, Warp Records and Kitty-Yo labels. Jimi has performed several times with the Avante Guarde big band Flat Earth Society.

In 2009 he contributed a cover of an Elektroids song to Warp20 (Recreated) compilation, as well as having his song "Paint the Stars" covered by Hudson Mohawke.

Discography

Jimi Tenor and his Shamans

Total Capacity of 216,5 Litres, 1988

Diktafon, 1989

Mekanoid, 1990

Fear of a Black Jesus, 1992

Solo

Europa, 1995

Sähkömies, 1994

Intervision, 1997

Venera EP, 1998

Organism, 1999 (Warp/Sire Records)

Out Of Nowhere, 2000

Cosmic Relief EP, 2001

Utopian Dream, 2001

Higher Planes, 2003

Beyond The Stars, 2004

Deutsche Grammophon ReComposed by Jimi Tenor, 2006

Live in berlin, 2007

With Kabu Kabu

Sunrise, 2006

Joystone, 2007

4th Dimension, 2009

With Tony Allen

Inspiration Information 4, 2009

External links

Official Site

Jimi Tenor & His Shamans Fanpage

Review of album "Joystone"

Category:1965 births Category:Living people Category:Finnish musicians Category:People from Lahti Category:Ubiquity Records artists

Name	Chris Cornell
Background	solo_singer
Birth name	Christopher John Boyle
Born	July 20, 1964Seattle, Washington, United States
Instrument	vocals, guitar, piano, drums, bass, mandolin, harmonica, banjo, mandola
Voice type	Heldentenor
Genre	Alternative metal, grunge, alternative rock, heavy metal, hard rock, funk metal, pop, contemporary R&B;
Occupation	musician, songwriter
Years active	1984–present
Label	SST Records (1984–88)Sub Pop/A&M; (1989–2000) Epic (2001–05)Suretone/Interscope (2007)Mosley Music/Interscope (since 2008)
Associated acts	Soundgarden, Center for Disease Control Boys, Temple of the Dog, Alice Mudgarden, Alice in Chains, Timbaland, M.A.C.C., Audioslave, Slash, Linkin Park, Carlos Santana (2010)
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Chris Cornell (born Christopher John Boyle; July 20, 1964) is an American rock musician best known as the lead vocalist for Soundgarden. He is also known as the former lead vocalist for Audioslave and for his numerous solo works and soundtrack contributions since 1998. He is known for his wide four octave vocal range, and powerful vocal belting technique. He was the founder and frontman for Temple of the Dog, the one-off tribute band dedicated to his former roommate, Andrew Wood. He has released three solo studio albums, Euphoria Morning (1999), Carry On (2007), and Scream (2009). Cornell was ranked 4th in the list of "Heavy Metal's All-Time Top 100 Vocalists" by Hit Parader. He performed the theme song to the James Bond film Casino Royale (2006), "You Know My Name".

Childhood and early life

Cornell was born and raised in Seattle, Washington and attended Christ the King, Catholic elementary school and Shorewood High School. His parents are Ed Boyle (a pharmacist from an Irish Catholic background) and Karen Cornell (an accountant from a Jewish background). He has five siblings: older brothers Peter and Patrick, and younger sisters Katy, Suzy, and Maggie. Peter, Katy and Suzy all performed in the band Inflatable Soule in the 1990s. Peter is currently the frontman for the New York-based rock band Black Market Radio. Katy performs as lead vocalist for the Seattle band Happy Hour Hero.

Cornell spent a two-year period between the ages of nine and eleven solidly listening to The Beatles after finding a large collection of Beatles records abandoned in the basement of a neighbors house. Cornell was a loner; however, he was able to deal with his anxiety around other people through rock music. Before becoming a successful musician, he worked at a seafood wholesaler and was a sous-chef at a restaurant named Ray's Boathouse.

In the early 1980s, Cornell was a member of a cover band called The Shemps that performed around Seattle. The Shemps also featured bassist Hiro Yamamoto. Following Yamamoto's departure from The Shemps, the band recruited guitarist Kim Thayil as its new bassist. The band's first recordings were three songs that appeared on a compilation for C/Z Records called Deep Six. In 1986, Sundquist, who by that point had a wife and a child, decided to leave the band and spend time with his family. The band subsequently signed with A&M; Records, becoming the first grunge band to sign to a major label. In 1989, the band released their second effort, and their first for a major label, Louder Than Love. Following the release of Louder Than Love, Yamamoto left the band to finish his Master's degree in Physical Chemistry at Western Washington University. He was replaced by former Nirvana guitarist Jason Everman. Everman was fired following Soundgarden's tour supporting Louder Than Love. In 1990, the band was joined by a new bassist, Ben Shepherd.

in Chicago, 2010 (L-R: Cornell, Matt Cameron, Ben Shepherd. Not pictured: Kim Thayil.)]] Along with Alice in Chains, Nirvana, and Pearl Jam, Soundgarden became one of the most successful bands from Seattle's emerging grunge scene in the early 1990s. With Shepherd, the new line-up recorded Badmotorfinger in 1991. The album brought the band to a new level of commercial success, and Soundgarden found itself amidst the sudden popularity and attention given to the Seattle music scene. Badmotorfinger included the singles "Jesus Christ Pose", "Outshined", and "Rusty Cage". The three singles gained considerable airtime on alternative rock radio stations, while the videos for "Outshined" and "Rusty Cage" gained considerable airtime on MTV. The song "Jesus Christ Pose" and its music video was the subject of widespread controversy in 1991, and the video was removed from MTV's playlist. "Rusty Cage" was later covered by Johnny Cash on his 1996 album, Unchained. It also appeared on the fictional radio station Radio X on the video game and in the 32-bit version of Road Rash. "Room a Thousand Years Wide" was released previously as a single in 1990, but not to promote the album. It was released (with the song "HIV Baby") as a 7" through Sub Pop's Single of the Month club a full year before the release of Badmotorfinger. The song was re-recorded for this album. Badmotorfinger was nominated for a Grammy Award for Best Metal Performance in 1992.

Superunknown became the band's breakthrough album. Upon its release in March 1994, Superunknown debuted at number one on the Billboard 200. The album launched several successful singles, including "Spoonman" and "Black Hole Sun", and granted Soundgarden international recognition. Superunknown achieved quintuple platinum status in the United States, triple platinum status in Canada, and gold status in the United Kingdom, Sweden, and the Netherlands. Rolling Stone gave Superunknown four out of five stars. Reviewer J.D. Considine said Superunknown "demonstrates far greater range than many bands manage in an entire career." He also stated, "At its best, Superunknown offers a more harrowing depiction of alienation and despair than anything on In Utero." Considine criticized "Black Hole Sun" and "Half", stating that the former is "not a very good song" while the latter "is the virtual definition of a B-side." Jon Pareles of The New York Times said that "Superunknown actually tries to broaden its audience by breaking heavy-metal genre barriers that Soundgarden used to accept." He added that "Soundgarden...want[s] something different from standard heavy metal." David Browne of Entertainment Weekly gave the album an A. He said, "Soundgarden is pumped and primed on Superunknown, and they deliver the goods." He praised it as a "hard-rock milestone-a boiling vat of volcanic power, record-making smarts, and '90s anomie and anxiety that sets a new standard for anything called metal." The album was nominated for the Grammy Award for Best Rock Album in 1995. Two singles from Superunknown, "Black Hole Sun" and "Spoonman", won Grammy Awards, and the music video for "Black Hole Sun" won a MTV Video Music Award and a Clio Award. Superunknown was ranked number 336 on Rolling Stone magazine's list of the 500 greatest albums of all time, and "Black Hole Sun" was ranked number 25 on VH1's list of the 100 greatest songs of the '90s.

The band's final album was 1996's self-produced Down on the Upside. The album spawned several singles, including "Pretty Noose", "Burden in My Hand", and "Blow Up the Outside World". The album was notably less heavy than the group's preceding albums, and marked a further departure from the band's grunge roots. Soundgarden explained at the time that it wanted to experiment with other sounds. David Browne of Entertainment Weekly said, "Few bands since Led Zeppelin have so crisply mixed instruments both acoustic and electric." However, tensions within the group arose during the sessions, with Thayil and Cornell reportedly clashing over Cornell's desire to shift away from the heavy guitar riffing that had become the band's trademark. Despite favorable reviews, the album did not match the sales of Superunknown. Due to tensions within the band, reportedly due to internal strife over its creative direction, Soundgarden announced it was disbanding on April 9, 1997. In a 1998 interview, Thayil said, "It was pretty obvious from everybody's general attitude over the course of the previous half year that there was some dissatisfaction."

1998–2000: Solo career

In 1998, Cornell began working on material for a solo album on which he collaborated with Alain Johannes and Natasha Shneider of the band Eleven. The album, entitled Euphoria Morning, was released on September 21, 1999. The album proved commercially unsuccessful although the album's single "Can't Change Me" was nominated for Best Male Rock Vocal Performance at the 2000 Grammy Awards. Euphoria Morning includes "Wave Goodbye", Cornell's tribute to his late friend Jeff Buckley. It has been noted that Euphoria Morning is influenced by Buckley's songwriting and distinctive vocal style. He also contributed the song "Sunshower" (a bonus track on the Japanese release of Euphoria Morning) to the soundtrack of the 1998 film, Great Expectations, and a reworked version of the track "Mission", retitled "Mission 2000", was used on the to the 2000 film, . In 2000, Cornell embarked on a tour in support of the album.

2001–2007: Audioslave

Audioslave was formed after Zack de la Rocha left Rage Against the Machine and the remaining members were searching for another vocalist. Producer and friend Rick Rubin suggested that they contact Cornell. Rubin played the remaining Rage Against the Machine band members the Soundgarden song "Slaves & Bulldozers" to showcase his ability. Cornell was in the writing process of a second solo album, but decided to shelve that and pursue the opportunity to work with Tom Morello, Tim Commerford and Brad Wilk when they approached him. Morello described Cornell: "He stepped to the microphone and sang the song and I couldn't believe it. It didn't just sound good. It didn't sound great. It sounded transcendent. And... when there is an irreplaceable chemistry from the first moment, you can't deny it." The quartet wrote 21 songs during 19 days of rehearsal and began working in the studio in late May 2001.

Their debut album, Audioslave, released in November 2002, spawned hits such as "Cochise", "Like a Stone" and "Show Me How to Live", and has reached triple platinum status in the United States. The band was nearly derailed before the album's release; Cornell was going through alcohol problems and a slot on the Ozzfest tour was canceled. In a San Diego CityBeat article, Cornell explained that he went through "a horrible personal crisis" during the making of the first record, staying in rehab for two months and separating from his wife. The problems were ironed out and he has remained sober since this time. The band toured through 2003, before resting in 2004 to record their second album.

Audioslave's second album, Out of Exile, was released in May 2005 and debuted at number one on the U.S. charts. The album has since gone on to achieve platinum status. The album features the singles "Out of Exile", "Be Yourself", "Your Time Has Come", and "Doesn't Remind Me". Cornell admitted to writing his most personal songs ever on this album, influenced by the positive changes in his life since 2002. He also described the album as more varied than the debut and relying less on heavy guitar riffs. but by the band's second album, Out of Exile, noted that they had established a separate identity. The album was received more favorably than Audioslave's debut; critics noted Cornell's stronger vocals, likely the result of quitting smoking and drinking, and pointed out that Out of Exile is "the sound of a band coming into its own." Allmusic praised the album as "lean, hard, strong, and memorable." The lyrics, however, were still a common complaint; musicOMH.com wrote that Cornell's lyrics "continue to border on the ridiculous." On May 6, 2005, Audioslave played a free show in Havana, Cuba. Audioslave became the first American rock group to perform a concert in Cuba, playing in front of an audience of 70,000. The band traveled to Havana on May 4 to interact with Cuban musicians. Cornell commented: "Hopefully, this concert will help to open the musical borders between our two countries." The 26-song set concert was the longest the band had ever played.

In early 2006 the band returned, recording their third album as they had written most of the material during the tour. The band released the album, titled Revelations, in September 2006. For Revelations, which was influenced by 1960s and 70s funk and R&B; music." The first two singles were "Original Fire" and "Revelations". Two of the songs from the third album, "Shape of Things to Come" and "Wide Awake" were also prominently featured in Michael Mann's 2006 film, Miami Vice, prior to the release of the album. Despite the exposure to other forms of media and the positive critical buzz for their third album, Audioslave did not tour behind the release. They went into hiatus to allow Cornell to complete "You Know My Name", the theme song for the 2006 James Bond film, Casino Royale, and Morello to pursue his own solo work under the moniker of The Nightwatchman.

All of Audioslave's lyrics were written by Cornell, while all four members were credited with writing the music. Their songwriting process was described by Wilk as "more collaborative" and "satisfying" than Rage Against the Machine's, which was "a battle creatively." Cornell, for his part, saw Soundgarden's songwriting method as inferior to Audioslave's. Cornell's lyrics were mostly apolitical; Audioslave's Morello referred to them as "haunted, existential poetry." They were characterized by his cryptic approach, often dealing with themes of existentialism, love, hedonism, spirituality and Christianity. and attended rehab after recording the debut album, Morello stated that Revelations was "the first record [Cornell] didn't smoke, drink or take drugs through the recording." However, Morello said: "Chris was stone sober during the making of our Out of Exile album. Chris was also sober during the making of Revelations and prior to recording he gave up smoking as well. I apologize for any confusion or concern that was stirred up by the original article. Sobriety can be a matter of life or death and Chris' courage in maintaining his health for years has been an inspiration."

News about Cornell's departure emerged in July 2006, when insiders stated that after the third album he would split for a solo career. The singer immediately denied the rumors, stating "We hear rumors that Audioslave is breaking up all the time. ... I always just ignore [them]." As the other three members were busy with the Rage Against the Machine reunion, and Morello and Cornell had each released solo albums in 2007, Audioslave was officially disbanded.

2007–2009: Solo revival

Cornell and composer David Arnold collaborated on the song "You Know My Name", which Cornell co-wrote and performed and which accompanies the opening titles for the 2006 James Bond film, Casino Royale. "You Know My Name" is the first theme song since 1983's Octopussy to use a different title than the film, the first ever sung by a male American, and the first ever title theme song that did not appear on the soundtrack album. Cornell is the first male performer since a-ha in 1987's The Living Daylights. It is the fourth title theme after Dr. No, On Her Majesty's Secret Service and Octopussy, that does not make any reference to the title of the film. "You Know My Name" won a 2006 Satellite Award in the category of Best Original Song, and a 2007 World Soundtrack Award in the category of Best Original Song Written Directly for a Film. The song was also nominated for Best Song Written for a Motion Picture, Television or Other Visual Media at the 2008 Grammy Awards. This song became the first song recorded for his solo album, which he began work on in 2007.

Cornell has done a number of meet and greet showings with his fanbase. On April 18, 2009, it was announced on his official website that he would be doing a meet and greet appearance at the "Electric Fetus" record store in Minneapolis, Minnesota. Fans who caught on to the message were able to meet Cornell for pictures and autographs before the concert at the "Myth" in Maplewood, Minnesota.

Though not officially released onto CD, an hour-long acoustic concert Cornell performed on September 7, 2006 at O-Baren in Stockholm, is widely available for download under the title Chris Cornell: Unplugged in Sweden. A promotional CD for his solo album, Carry On, was released in March 2007, entitled The Roads We Choose - A Retrospective. The 17-song CD included songs from Soundgarden, Temple of the Dog, Audioslave and Cornell's solo work.

On June 5, 2007, Cornell released his second solo album, Carry On, produced by Steve Lillywhite. It debuted at number 17 on the American Billboard charts. Among the artists who accompanied him on his second solo release was friend Gary Lucas, who contributed acoustic guitar to some of the tracks. Cornell has stated that he is always writing, and that there are some songs that he was not able to put onto an Audioslave album. While recording his second solo album, Cornell was involved in a motorcycle accident. He was apparently "rear-ended by a truck in L.A.'s Studio City while riding his motorcycle" and "catapulted 20 feet into the air." He was able to walk away from the accident, but had severe cuts and bruises. He returned to the studio later that day.

In 2007, Cornell appeared as support to Aerosmith on at least two legs of their 2007 world tour—Dublin, London, and Hyde Park—and to Linkin Park in Australia and New Zealand. These shows formed part of his own ongoing world tour which began in April 2007 and continued into 2008. Cornell has described his touring band—comprising guitarists Yogi Lonich and Peter Thorn, bassist Corey McCormick and drummer Jason Sutter—as "musicians that could get the whole picture" playing music by Soundgarden and Audioslave, as well as his solo material.

In 2008, Cornell was featured on the Main Stage of Linkin Park's Projekt Revolution tour. Joining Linkin Park and Cornell on the Main Stage were Busta Rhymes, The Bravery, and Ashes Divide. The Revolution Stage featured Atreyu, 10 Years, Hawthorne Heights, Armor for Sleep, and Street Drum Corps. During this tour, Cornell has stated that he plans to "jump on stage" with other artists as the opportunity arises; this may set the stage for future Cornell collaborations, outside his work with Timbaland. Throughout the tour, Cornell collaborated with Chester Bennington from Linkin Park while performing "Hunger Strike", and with Street Drum Corps for a number of his Soundgarden tracks. While Linkin Park would perform their Grammy-winning song "Crawling", he would appear on stage singing the second verse of the song, the outro, and harmonies Aaron Lewis provided for the Reanimation version.

Cornell worked with producer Timbaland on his most recent album, Scream, which was released on March 10, 2009. Timbaland has referred to the recording sessions as "The best work I've done in my career," and predicted that Cornell will be the "first rock star in the club." Cornell called the new album "a highlight of my career." The album was largely panned by critics but was the highest charting album of Cornell's solo career, reaching # 10 on the Billboard 200.

On April 2, 2009, Cornell took over Atlanta Rock station, Project 961, WKLS-FM. For 24 hours the station became "Chris-FM" and included a two hour special of Cornell DJing and playing his favorite songs of his career with the stories behind them leading up to a rebroadcast of his solo show from the previous night. On September 11, 2009, Cornell performed John Lennon's "Imagine" on The Tonight Show with Conan O'Brien. On October 30, 2009 it was reported that Cornell is working with Jordan Zadorozny and Michael Friedman to rework the Scream album, although this remains unconfirmed. Cornell's voice is also sampled on the song "Mister Dirt" from Joshua David's album "Good. Night. Melody." which was released on November 17, 2009.

2010: Soundgarden reunion

On January 1, 2010, Cornell alluded to a Soundgarden reunion via his Twitter account, writing: "The 12-year break is over and school is back in session. Sign up now. Knights of the Soundtable ride again!" The message linked to a website that features a picture of the group performing live and a place for fans to enter their e-mail address to get updates on the reunion. Entering that information unlocks an archival video for the song "Get on the Snake," from Soundgarden's second studio album, 1989's Louder Than Love.

In April 2010, Soundgarden announced plans to headline Lollapalooza 2010. Soundgarden made the announcement through their website and email list. On April 16, 2010, Soundgarden held a secret show at the Showbox Theater on First Avenue in downtown Seattle, Washington, publicized via the band's mailing list. The show was billed as Nudedragons, an anagram for Soundgarden. Asked in August 2010 if Soundgarden will record new material, Cornell replied, "it would be exciting to record one song, to hear how Soundgarden-ish that might be this much time later. But for me, it's been more of a trip relearning the songs and playing them together. Some of the songs we're approaching we've never played live."

Soundgarden made their first television appearance since their reunion on Conan O'Brien's second episode of Conan November 9,2010 on TBS

Other musical projects

Center for Disease Control Boys

From 1986 to 1987, Cornell was also a member of the satirical Western swing band Center for Disease Control Boys.

Temple of the Dog

While still in Soundgarden, Cornell recorded an album with members of what would become Pearl Jam. This collaboration went under the name Temple of the Dog, and the self-titled album was released in 1991. The album is a tribute to their mutual friend, and Cornell's former roommate, Andrew Wood. Wood, the former lead singer of Mother Love Bone, died of a heroin overdose the year before. Jeff Ament and Stone Gossard of Mother Love Bone teamed up with Mike McCready, Dave Krusen, and new vocalist Eddie Vedder in 1990, forming Pearl Jam. Temple of the Dog has gone on to sell more than a million copies, thanks in large part to the singles "Say Hello 2 Heaven" and "Hunger Strike", the latter of which features a duet between Cornell and Vedder. This was the first time Vedder was recorded professionally. During a 2003 Pearl Jam show at the Santa Barbara Bowl, Cornell appeared as a surprise guest. After playing a short acoustic set, Cornell joined Vedder and the rest of the band to perform "Hunger Strike" and "Reach Down". On October 6, 2009, Cornell made a surprise appearance during a Pearl Jam concert at the Gibson Amphitheater in Los Angeles. The reunited Temple of the Dog played Hunger Strike. At the end of the concert, Cornell took a bow with the band along with Jerry Cantrell of Alice in Chains, thus having three of the four major grunge bands of the early 90's represented on stage, with only Nirvana missing.

Alice Mudgarden

Cornell, together with Mark Arm of Mudhoney, contributed vocals on the Alice in Chains song "Right Turn" from the 1992 EP, Sap, although the band given credit for this song is Alice Mudgarden.

M.A.C.C.

In 1992, Cornell and three other former members of Temple of the Dog played under the name M.A.C.C., recording the song "Hey Baby (New Rising Sun)" for the 1993 album, .

Collaborations

Cornell worked as a co-producer and backing vocalist on the Screaming Trees' 1991 album, Uncle Anesthesia. He acted in a cameo role and an onstage performance in Cameron Crowe's 1992 Seattle-based film, Singles. He also contributed his solo song "Seasons", and Soundgarden's song "Birth Ritual", to the Singles soundtrack. Cornell contributed vocals on Alice Cooper's "Stolen Prayer" and "Unholy War" (which he also wrote) from the 1994 album, The Last Temptation. In 1997, Cornell collaborated with Eleven on a rendition of the song, "Ave Maria", for the Christmas compilation album, A Very Special Christmas 3. Cornell has also performed live with the band Linkin Park.

It was incorrectly believed (for many years) that Cornell had written the Eleven song "Someone to Die For" on the 2004 Spider-Man 2 soundtrack, but this was corrected in an interview in April 2007. The song is performed by Jimmy Gnecco of Ours and Brian May of Queen. Cornell had recorded a demo of the song some time earlier, which was released only to members of the Eleven street team.

Cornell co-wrote (with Brian Howes) David Cook's first post-American Idol album single, "Light On", released in 2008. And in 2009, he contributed vocals on the song, "Mister Dirt", from the album, Good.Night.Melody, by Joshua David. Cornell sang one song, (which he co-wrote) on Slash, Slash's solo record released in April 2010. The song is called "Promise" and it was premiered at amazon.com on March 26, 2010. He contributed vocals on the song, "Lies", on the 2010 album, Third and Double, by Gabin which was subsequently released as a single in October 2010. Cornell appears on the Carlos Santana album , where he sings on the cover of Led Zeppelin's "Whole Lotta Love."

Though the Soundgarden reunion may have put these rumors to rest, internet buzz has also linked Cornell to future collaborations with super-group Velvet Revolver. The belief is that Cornell is a good fit to fill Velvet Revolver's empty frontman position (previously held by Scott Weiland of Stone Temple Pilots). Similar rumors have also followed Cornell about a reunion with former band Temple of the Dog. Such a reunion would allow Cornell to collaborate with former band mate and good friend Eddie Vedder of Pearl Jam. Yet, when asked about the rumors of a Temple of the Dog reunion linked to Soundgarden and Pearl Jam shows by WAAF's host Mistress Carrie, Cornell joked that Matt Cameron, who drums for all three bands, would have to go and train in a similar fashion to Bruce Wayne in Batman Begins.

Other work

Chris Cornell made a cameo in the 1992 movie Singles. Cornell was the face of fashion producer John Varvatos' 2006 ad campaign. He recently became a restaurateur with the opening of his restaurant, Black Calavados, in Paris. He is also the owner of the music publishing company You Make Me Sick I Make Music.

Cornell has optioned Phil Carlo's true crime book The Night Stalker: The Life and Crimes of Richard Ramirez, with plans to turn it into a movie. Cornell is collaborating with Carlo to produce the screenplay.

Personal life

Cornell was previously married to Susan Silver, the manager of Alice in Chains and Soundgarden. He had a daughter with Silver, Lillian Jean, in June 2000. He and Silver divorced in 2004. In December 2008, Cornell reported via his official website that he had finally won back his collection of 15 guitars after a four-year court battle with Silver.

He is currently married to Vicky Karayiannis (Βίκυ Καραγιάννη), a Paris-based American publicist of Greek heritage. She gave birth to his second daughter, Toni, in September 2004, and his third child, Christopher Nicholas, in December 2005.

Discography

Chris Cornell has released three solo albums. His first band Soundgarden, produced five albums, five EPs and a greatest hits compilation. He released three albums with Audioslave and one album with Temple of the Dog. Despite this large discography he has only released one retrospective compilation which was given a limited release. Cornell has also produced an album for Screaming Trees and had his music featured on one mixtape.

Solo releases

Euphoria Morning (1999)

Carry On (2007)

Scream (2009)

Soundgarden

Temple of the Dog

Temple of the Dog (1991)

Audioslave

Other appearances

;Vocals

1992: Alice in Chains - Sap (Co-lead Vocals on "Right Turn")

1994: Alice Cooper - The Last Temptation (Backing Vocals on "Stolen Prayer" and "Unholy War")

2009: Joshua David - Good.Night.Melody (Vocals on "Mister Dirt")

2010: Slash - Slash (Vocals on "Promise")

2010: Gabin - Third and Double (Vocals on "Lies")

2010: Carlos Santana - ( Vocals on "Whole Lotta Love")

;Producer

1991: Uncle Anesthesia by Screaming Trees

;Mixtapes

2009: Chris Cornell and Prophet – Scream: The Mixtape – presented by DJ Skee

Awards and nominations

References

External links

Category:1964 births Category:1980s singers Category:1990s singers Category:2000s singers Category:2010s singers Category:American people of Irish descent Category:People of Jewish descent Category:American male singers Category:American rock guitarists Category:American rock singers Category:American singers Category:Songwriters from Washington (U.S. state) Category:American tenors Category:Audioslave members Category:Blue-eyed soul singers Category:Grunge musicians Category:American musicians of Irish descent Category:Living people Category:Musicians from Washington (U.S. state) Category:People from Seattle, Washington Category:Soundgarden members Category:Sub Pop artists Category:Temple of the Dog members